<html>
    <head>

    </head>
    <body>
        <script>
            var a="123";
            var b="456";
            document.write(a+b+"<br />");
            var num1=parseInt(a);
            var num2=parseInt(b);
            document.write(num1+num2+"<br />");

            document.write(isNaN('abc')+"<br />");
            document.write(isNaN('123')+"<br />");


            document.write(isFinite(1/0)+"<br />"); 
			document.write(isFinite(1)+"<br />");

            var a=10;
            var b=20;
            var str="alert('Hello world'+(a+b)')";
            eval(str);

            var str1 = "http://www.baidu.com/s?=java 习题";
			document.write(str1);
			document.write("<br />");
			var str2 = encodeURI(str1);
			document.write(str2);
			document.write("<br />");
			var str3 = decodeURI(str2);
			document.write(str3);
			document.write("<br />");

            
        </script>
    </body>
</html>